The present disclosure relates to the field of brake systems in general. An electro-hydraulic motor vehicle brake system is described in concrete terms. Modern motor vehicle brake systems operate according to the “brake-by-wire” principle. This means that a hydraulic pressure is built up on the wheel brakes by way of a hydraulic pressure generator, independently of a foot force. In addition to the hydraulic pressure generator, brake systems of this type generally comprise a brake pedal interface with sensor technology for detecting an actuation of a brake pedal, a simulator device, which is coupled to the brake pedal interface, for simulating a realistic pedal reaction behaviour and a plurality of hydraulic valves.
Brake-by-wire brake systems have a plurality of advantages. For example, they are excellently suited for the integration of energy recovery systems. Furthermore, as a result of such brake systems, it is possible to better control a build-up of pressure for individual wheels and to better integrate vehicle dynamics management programs (e.g. ABS-, ASR-, ESP-programs).
Examples for the realisation of brake-by-wire brake systems are known from WO 2012/062393 A1 and WO 2012/152352 A1. The hydraulic pressure generators taught therein comprise a cylinder-piston device for hydraulic pressure generation and an electromechanical actuator acting on the piston of the cylinder-piston device. The electromechanical actuator is arranged downstream of the cylinder-piston device and is coupled directly to the piston of the cylinder-piston device. The piston can therefore be actuated directly by way of the actuator, thereby enabling a hydraulic pressure to build up on the wheel brakes independently of a foot force.
The cylinder-piston device can furthermore be coupled by way of a force transmission device to a pedal interface arranged downstream of the cylinder-piston device and the electromechanical actuator. In an emergency operation of the brake system (e.g. in the event of a failure of the electromechanical actuator or its control means), the force transmission device enables a mechanical coupling of the cylinder-piston device to the brake pedal interface to enable an actuation of the piston of the cylinder-piston device by means of the foot force applied to the pedal interface (push-through operation).
In some realisations, the serial arrangement of the cylinder-piston device, electromechanical actuator and pedal interface results in a relatively long axial extent of the assembly formed thereby. Correspondingly large installation spaces have to be provided in the motor vehicles. Hydraulic pressure generators with a long axial extent can furthermore have a negative influence on the crash safety of a vehicle. The architecture of the hydraulic pressure generators described in WO 2012/062393 A1 and WO 2012/152352 A1 also calls for the installation of powerful actuators which are capable of applying sufficiently high piston actuating forces to generate the necessary hydraulic pressures in the brake-by-wire braking operation.